Up next, we'll be focusing on you and your true love - your smartphone. Think about it. Are you lost without it? Inconsolable if the two of you are separated? Willing to walk into a lamppost rather than look up while texting? Is it the object of your desire? Isn't it?

And your romance is about to be taken to a new level. Google has already released its new Google Glass to developers, and it could be for sale within the year - a pair of glasses that can take pictures, translate what you say into Chinese, display the weather, walking directions, texts, emails, or the height of the Eiffel Tower on a tiny, little screen above your eye.

Now the two of you need never be separated for even one moment. Your virtual life can now join your real life. Some might say your virtual life can become your real life. So where do we draw the line between these two virtual worlds and our real world? Do we even have a choice?

My next guest says our technology-addicted lifestyle and our nonstop multitasking may be affecting our ability to concentrate, manage our emotions, even think creatively. Clifford Nass is author of "The Man Who Lied to His Laptop." He's also professor of communication here at Stanford. Welcome back.

DR. CLIFFORD NASS: Good to see you again.

FLATOW: Excuse me for my cough. So are you fearful about us losing contact with what real life is once these things happen?

NASS: I'm fearful and optimistic. Fearful because technology, media technologies in particular are incredibly seductive, but optimistic because humans are pretty cool and seem to work their way out of things.

FLATOW: How distracted are we today?

NASS: Remarkably so. The top 25 percent of Stanford students are using four or more media at one time whenever they're using media. So when they're writing a paper, they're also Facebooking, listening to music, texting, Twittering, et cetera. And that's something that just couldn't happen in previous generations even if we wanted it to.

FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY from NPR.

But people used to say, oh, television. You know, that's the thing that's going to keep us distracted. And oh, radio, that - before that. Oh, this sort of thing, that sort of thing. What makes this different?

NASS: Well, it's true that radio and television do distract us. People have television on chronically while they're doing other activities, so that happened. The difference was the number of televisions in the home was rather limited, and so kids in particular didn't always have control of the box. We now see a dramatic growth so that kids have TVs in their own room.

We also have a number of new devices. The number of young people, as well as older people, who have a cellphone and a tablet and a laptop and a personal computer and a stereo system and a computer and et cetera, has just exploded.

FLATOW: Yeah. And now they can have them all on a pair of glasses in one spot.

NASS: So it's not clear whether that'll be a substitute or that'll be yet one more device in which yet another screen, yet another input mechanism they can have.

FLATOW: Yeah, but there are people who say, you know, I'm great at multitasking. I can - I have no problem with this. What do you say to that?

NASS: The research is almost unanimous, which is very rare in social science, and it says that people who chronically multitask show an enormous range of deficits. They're basically terrible at all sorts of cognitive tasks, including multitasking. So...

(LAUGHTER)

NASS: ...in our research, the people who say they're the best at multitasking because they do it all the time. It's a little like smoking, you know, saying, I smoke all the time, so smoking can't be bad for me. Unfortunately, it doesn't work that way.

FLATOW: And it's quite noticeable on tests. You can actually test for that and see the differences going on.

NASS: Yeah. It's...

FLATOW: Yeah.

NASS: Mm-hmm. Yeah. So we have scales that allow us to divide up people into people who multitask all the time and people who rarely do, and the differences are remarkable. People who multitask all the time can't filter out irrelevancy. They can't manage a working memory. They're chronically distracted.

They initiate much larger parts of their brain that are irrelevant to the task at hand. And even - they're even terrible at multitasking. When we ask them to multitask, they're actually worse at it. So they're pretty much mental wrecks.

(LAUGHTER)

FLATOW: Wow. But they don't think they are.

NASS: No. You're...

FLATOW: And that's the danger, right?

NASS: That's right. No, they actually think they're more productive. They actually think they tend to - and most notably, they think they can shut it off, and that's been the most striking aspect of this research.

We - the people we talk with continually said, look, when I really have to concentrate, I turn off everything and I am laser-focused. And unfortunately, they've developed habits of mind that make it impossible for them to be laser-focused. They're suckers for irrelevancy. They just can't keep on task.

FLATOW: So they - all because they have been multitasking. They've lost that ability to focus on one thing.

NASS: That's precisely right. Our brains have to be retrained to multitask and our brains, if we do it all the time - brains are remarkably plastic, remarkably adaptable. We train our brains to a new way of thinking. And then when we try to revert our brains back, our brains are plastic but they're not elastic. They don't just snap back into shape.

FLATOW: Can you retrain them to come back?

NASS: We would love to know. It's very hard because frankly in the few studies we've tried to do it, people refuse. It's almost impossible to get a group of people who believe their lives are built around multitasking to stop for two weeks to actually see whether their brains have changed.

FLATOW: What an addiction. It must be really - is it correct to call it an addiction?

NASS: There's some debate about what the term addiction means, but by any of the behavioral measures of addiction, these people are absolutely, positively addicted. If you're talking about the biochemical stuff, it's much more complex.

FLATOW: All right. We're going to talk a lot more with Clifford Nass, author of "The Man Who Lied to His Laptop." That's something to do. We'll be right back after this break. If you're in the audience, step up to the mic. We welcome your questions. Stay with us. Be right back with multitasking, yes or no, after this break. We'll be right back. I'm Ira Flatow. This is SCIENCE FRIDAY from NPR.

(SOUNDBITE OF MUSIC)

FLATOW: This is SCIENCE FRIDAY. I'm Ira Flatow. We're talking with Clifford Nass, author of "The Man Who Lied to His Laptop." He is also professor of communications here at Stanford University in California. And we're talking about multitasking. And I think the topic of conversation now is so focused on people driving and, well, tweeting and talking. How dangerous is that? What is going on in that car seat?

NASS: The evidence shows that basically tweeting, Twittering, texting, even speaking on the phone whether it's hands-free or not is incredibly distracting. And the core problem is that to our surprise, what we found is when people are driving and talking on the phone or texting, that other task becomes what we call the primary task, the thing their brain focuses on. And driving becomes the sort of secondary, yeah, I'll pay attention when I want to.

So ironically even though everyone's terrible about it, high multitaskers do better because they're distracted by the road.

(LAUGHTER)

NASS: So these low multitaskers focus on the conversation, the high multitaskers every now and then go oh, my goodness, a road - something I can look instead of focusing on what I want to. So it's a problem for everyone and without the advent of autonomous cars, it's going to be a continuing problem.

FLATOW: But now we also have other little screens there. Beside the road, you've got a little screen for your, you know, your audio or video products, your radio.

NASS: The problem is, as people have become - love screens. So the more screens you put in the car, the more people want to look at the screen, and the basic problem is the windshield is just another screen, and as screens go, not all that an exciting one. So we have this true design challenge that we've never encountered before, which is the entire field of automotive design has to switch from how can I, the designer, stop distracting you because you really want to pay attention to the road, to a radically different world in which the driver says I don't want to pay attention to the road, and the auto designer has to say how can I force you back onto paying attention to the road? It's a really exciting challenge.

FLATOW: And I can see why then people would like to design a driverless car, because then they can sell you products that you can use in your car when you're not having to look at the road.

NASS: You're absolutely right. The worst problem for advertising in a car is people just don't pay enough attention to advertising. So what autonomous cars will allow, if they're truly autonomous or automated 24/7, is for people to pay attention to the ads or the content. The problem is if the car hits a moment in which you have to be thrust back into the driver's seat, right, actually driving, that's another enormous challenge. How do we reorient the driver to the road? And that's something we're working very hard on, and it's difficult.

FLATOW: OK. Let's go to the audience here. Yes?

LARRY: Yes. My name is Larry and, Clifford, your comment was interesting. And aside from driving which is obviously a not-good multitasking environment, can you actually train people adequately to multitask effectively or are they all going to be distracted no matter what they're doing?

NASS: We don't know. We, so far, have not found people who are successful at multitasking. There's some evidence that there's a very, very, very, very small group of people who can do two tasks at one time but there's actually no evidence that anyone can do even three. And remember, the top 25 of Stanford students are doing four or more, and the top 25 percent of tweens - at least tween girls - are doing three or more. So it's a pretty bleak scenario.

FLATOW: Does this affect your creativity at all?

NASS: It's one of the big questions we're looking at. We suspect so. The argument had been oh, creative people suck in everything and therefore that's what they're doing. But it's actually not an accurate description of creativity. Creative people do suck in a lot of things, but then they focus really hard on finding relationships that are not obvious. These high multitaskers don't focus very hard. So we suspect they're actually going to be less creative, although we haven't done that research yet.

FLATOW: So multitasking is a misnomer then? It's like multiswitching, you say? You're switching back and forth and not doing things at the same time.

NASS: When it comes to media, sure. So we all, of course, are breathing while we're eating while we're doing other things. But when it comes to media or our prefrontal cortex, the thinking part of our brain, yes, we're basically switching back and forth. We only have about three bits' worth of information we can mess with at any one time.

FLATOW: Wow. We need new heads.

(LAUGHTER)

NASS: I'll take one.

DAVID: Hi. I'm Dante Simone's(ph) father. And it's...

FLATOW: Do you have a name of your own?

DAVID: David.

FLATOW: David, okay.

NASS: You have a great child.

DAVID: I - it seems like in the last 10 years there's been a real interest in ADD and ADHD. And I wondered if you had been studying any correlations between multitasking and specifically technology multitasking and the rise of diagnosis of ADD.

NASS: We're starting to. So it turns out that attention deficit is a bit of a misnomer. Pretty much everyone has the same amount of attention to allocate. It's where we allocate it. And what people with attention deficit do is they spread their attention over what we would call an inappropriately large span of stimuli, whereas non-attention-deficit people focus. That's exactly what multiple media and multitasking train you to do, spread your attention over a very large - so there's very likely relationships. There are, of course, physiological correlates of ADD.

We are starting a program to look at the brain scans of individuals diagnosed with ADD as associated with brain function and high multi-taskers, but we haven't done that research yet.

DAVID: And just a quick comment, last week we saw Mick Jagger and Keith Richards on stage. But seeing Flora and Ira on stage is way cooler.

FLATOW: Thank you. Thank you.

(APPLAUSE)

FLATOW: Question about anything practical, you know, let's talk about on the most basic level. We're flooded with email all the time. You sit there, you're working, email, another pops up. It's distracting, it's distracting again. What's the best way to handle that?

NASS: We think, although we haven't directly tested it, that the 20-minute rule is right, which is if you're going to engage in email, commit to doing 20 minutes of email. And when we propose this, people say email's not worth 20 minutes. My God, email's just such a useless activity. So then ask people to clock how many minutes a day they use email - 100, 200, but in little bits and bleeds. So it turns out you're much more efficient at the email, and more importantly, you're treating your brain better when you get off email if you do one focused email patch every interval for at least 20 minutes.

FLATOW: Flora is - you've been outed, Flora, here in the auditorium. Flora Lichtman is here with us. She's going to do her Video Pick of the Week, but I know that you must be thinking that you're a multitasker also.

FLORA LICHTMAN, BYLINE: I'm worried.

I'm very worried, Dr. Nass. Can I go back? I don't know.

FLATOW: Yeah. I mean, that's what people want to know. Can they be rehabilitated, right?

NASS: Well, that's our infinite money question. The infinite money question is, can we take people, scan their brains, have them change their behaviors over time and steadily show improvements in their brain function, and I hope to heck the answer is yes.

FLATOW: Well, you know, we've talked about addiction before, and when we have addiction experts on, they say that there are new pathways that are created in your brain. Those are the kinds of pathways you'd be looking for to see if they exist if you're multitasking?

NASS: There's a lot of different things; one is localization. When we give tasks, you're using the part of the brain that's effective and not using the part of brain that's ineffective.

We can look at use of the front part of the brain called the prefrontal cortex. We can look at even things like emotion management. There's evidence that high multitaskers have difficulty with managing their emotion. So this really spans everything we do, because after all, thinking is about everything we do.

FLATOW: So, you optimistic that this - we can get control of this problem, or is it going to get worse before it gets better?

NASS: As a psychologist, I'm extremely optimistic. As a communications scholar who knows how seductive media is, as you know, being in media, it's a tough call.

FLATOW: Yeah. And you have to be - even the 20-minute rule on your email is something that you have to practice. You have to put up a distraction to tell you that take that 20 minutes. A little note will have to pop up, right?

NASS: (Laughing) It is amazingly hard. I mean, I do this research. I lived with these people. I look at what it does to my brain and other people's brains. And I still just want to glance over at an email. It's tough to say no.

FLATOW: Is it something we should teach people now that all kids are, you know, they start out in life doing all this kind of thing. We should have, you know, sessions in school as part of teaching curricula?

NASS: Look, you know, we worry particularly about the very young. There's evidence, for example, that children, while breastfeeding, if the television is on, watch television, because after all, a mother has one lousy face and one lousy voice. Television has lots of faces and lots of voices. So...

FLATOW: Speak about your own mother.

(LAUGHTER)

NASS: It's Mother's Day coming up. (unintelligible) my mother. The problem is we give young children tablets and other media, as well as TV. Kids at early - the average nine-year-old has a cellphone. The penetration of media into younger and younger age groups without any attempt to train them how to manage this stuff is really threatening. And when television came in, of course, again, there was only - it was a medium that was essentially shared by a family. You had one in your living room. Now kids are isolated with media. There's no training. There's no practice. It is a very worrisome trend.

FLATOW: Let's see if we can get one question in before we have to go yet.

UNIDENTIFIED WOMAN: Hi. So I was wondering if you could parse out the difference between multitasking with technology versus just general multitasking, because it seems that evolutionarily it would be advantageous for humans to be able to multitask very well. You think of a mother who's able to tend to her child while also gathering food or something like that. So is there something in particular about technology that is really detrimental?

NASS: It's a wonderful question. So it turns out for non-media tasks, women are better than men in multitasking. For media tasks, they're similar. Our brains are built to receive many stimuli at one time, but they're related stimuli. The problem with multitasking is not that we're writing a report of Abraham Lincoln and hear, see pictures of Abraham Lincoln and read words of Abraham Lincoln and see photos of Abraham...

The problem is we're doing a report on Abraham Lincoln and tweeting about last night and watching a YouTube video about cats playing the piano, et cetera.